Biosynthetic features and properties of xylose isomerases from Arthrobacter nicotianae, Escherichia coli, and Erwinia carotovora subsp. atroseptica

The characteristics of xylose isomerase biosynthesis in the bacteria Arthrobacter nicotianae BIM B-5, Erwinia carotovora subsp atroseptica jn42xylA, and Escherichia coli HB101xylA have been studied. The bacteria produced the enzyme constitutively. Out of the carbon sources studied, D-glucose and D-xylose were most favorable for the biosynthesis of xylose isomerase in E. carotovora subsp. atroseptica, but the least appropriate in terms of the enzyme production efficiency in E. coli. Minimum and maximum levels of xylose isomerase formation in A. nicotianae were noted, respectively, during D-xylose and sucrose utilization. An addition to the D-xylose-containing nutrient medium of 0.1–1.5% D-glucose did not affect the enzyme synthesis in A. nicotianae, but suppressed it in Erwinia carotovora subsp. atroseptica (by 7% at the highest concentration) and Escherichia coli (by 63 and 75% at concentrations of 0.1 and 1.0%, respectively). The enzyme proteins produced by the bacteria exhibited the same substrate specificity and electrophoretic mobility (PAGE) as xylose isomerase A. nicotianae, although insignificant differences in the major physicochemical properties were noted.     

New species of Passiflora subg. Plectostemma and subg. Tacsonia (Passifloraceae)

Five new species of Passiflora subgenera Plectostemma and Tacsonia from Ecuador are described, viz. P. discophora, P. monadelpha, P. subpurpurea, P. hirtiflora and P. sanctaebarbarae . Section Discophora of subg. Plectostemma is proposed.     

Development of a diagnostic test system for detecting soluble staphylococcal antigens by an immunoenzyme method

ELISA is used for detecting the soluble staphylococcal antigen in patients with purulent septic infections. The optimum conditions for the assay have been established: the dose of staphylococcal gamma globulin for plate sensitization should be 5.0-10.0 micrograms/ml, the pH of the buffer solution 9.6-10.0, the time and temperature of incubation 18-20 hours at 4 degrees C or 5 hours at 37 degrees C. The possibility of using plates manufactured in the USSR has been shown. The sensitivity of the above diagnostic test system is 0.005 microgram/ml.     

Somatic embryogenesis in cell suspension culture of carnation (Dianthus caryophyllus L.)

Somatic embryogenesis and plantlet formation were obtained from 60–75 day old cell cultures of carnation. Callus was generated on MS basal medium supplemented with 2,4-dichchlorophenoxy acetic acid (2,4-D). Removal of 2,4-D during subsequent subculturing of cell suspensions resulted in formation of embroids. These somatic embryos originated from single cells and their early development proceeded normally with clearly defined apical and root meristems. Some embryos developed into plants and were acclimatized to ex vitro conditions.     

Role of different lymphoid tissues in the initiation and maintenance of DNA-raised antibody responses to the influenza virus H1 glycoprotein.

Antibody responses in mice immunized by a single gene gun inoculation of plasmid expressing the influenza virus H1 hemagglutinin and in mice immunized by a sublethal H1 influenza virus infection have been compared. Both immunizations raised long-lived serum responses that were associated with the localization of antibody-secreting cells (ASC) to the bone marrow. However, the kinetics of these responses were 4 to 8 weeks slower in the DNA-immunized than in the infection-primed mice. Following a gene gun booster, the presence of ASC in the inguinal lymph nodes, but not in other lymph nodes, revealed gene gun responses being initiated in the nodes that drain the skin target site. Both pre- and postchallenge, the DNA-immunized mice had 5- to 10-times-lower levels of antibody and ASC than the infection-primed mice.